because after a bit of that I see real improvements in my regular runs. Time is better and endurance is too.
I'm also a fan of an app my daughter's boyfriend found. It's called Zombie Run Game and it's fun. You can use it on the road or in the gym. It's an immersible game where you are in a zombie filled hellscape and you have to run. I love when the voice yells RUN!!! RUN!!! Even on the elliptical it kept me distracted and I didn't get bored. Well worth $4. Especially given my ADD. I don't do bored well.